The present invention relates to preparation of fuel for a fuel cell power plant and, more particularly, to a preferential oxidation reactor and process whereby carbon monoxide in a reformate stream is converted to carbon dioxide.
Proton exchange membrane (PEM) fuel cells and PEM fuel cells stacks use hydrogen for fuel. It is conventionally quite difficult to obtain pure hydrogen as fuel, however, and therefore hydrogen rich gas mixtures are obtained through reforming of various hydrocarbon fuels. Hydrocarbon fuel is typically treated through a series of reactors, for example a reformer and a shift converter, and then fed as fuel to a PEM fuel cell power plant. Such processing of fuel typically results in a stream containing hydrogen as well as carbon dioxide, water, nitrogen and carbon monoxide. Carbon dioxide and water can be readily and easily removed but it is carbon monoxide removal that is key because carbon monoxide acts as a poison on the anode of PEM cells. However, conventional carbon monoxide removal processes such as pressure swing adsorption systems and the like add greatly to the expense and size of equipment needed.
Attempts to preferentially oxidize carbon monoxide in the reformate stream have been made. However, existing problems include parasitic consumption of hydrogen during this process, introduction of additional nitrogen to the reformate stream and others.
It is therefore the primary object of the present invention to provide a preferential oxidation reactor and process whereby these and other problems are overcome.
Other objects and advantages of the present invention will appear hereinbelow.